The present invention relates to a method and system for utilizing a power transmission network as a communication network along with its normal power transmission function, and, particularly to such a network in which the magnetic field component of the electromagnetic radiation traveling along the power transmission line through a power distribution network is utilized to transmit information between subscribers, including telephonic voice communication.
The use of power transmission lines as a communication media is well known in the art with some of the earliest work dating back to the 1930""s in an effort to provide telephone communication to rural areas which had not yet been served by telephone lines, such as the type of prior art systems described in U.S. Pat. Nos. 2,032,360; 2,264,395; and 2,264,396. These systems, which employed carrier waves superposed on the electrical component of the electromagnetic radiation carried over the power transmission line, were strictly analog in nature and were not particularly successful because of the inherent limitations of the analog bandwidth, signal attenuation, and the inability to handle more than one call at a time. As further attempts were made to develop an analog based system, it was discovered that unsatisfactory radiation from the power transmission line would result at carrier frequencies in excess of 300 KHz which would interfere with long wave radio signals, limiting such systems to a frequency range of 30 KHz to 300 KHz. One such attempt at developing an analog based system, described in U.S. Pat. No. 5,684,450, permitted the use of carrier frequencies greater than 1 MHz for transmission between power transformers, however, it was found that electromagnetic noise from the power lines interfered with the information signals being transmitted, such as each time an electrical appliance connected to the power distribution network was switched on. The need to transmit information through the power transformers also proved an impediment to a successful power line communication system. Attempts have also been made to overcome these problems through the use of digital signal transmission instead of an analog carrier wave, but still utilizing the electrical component of the electromagnetic radiation carried over the power transmission line, such as disclosed in U.S. Pat. Nos. 5,554,968; 5,559,377; and 4,471,399, as well as the use of digital packets to try to overcome the noise problem, but these attempts have also been unsatisfactory and/or too costly.
Because of the well established power transmission infrastructure, and the increasing need for higher speed, higher capacity, and greater distribution of information of all types over great distances, particularly telephonic communications today, there is a continuing and increasing need to develop a satisfactory and cost effective communication system which takes advantage of the vast and well established power transmission line distribution network already in place throughout the United States and the world at large. The disadvantages of the prior art are overcome by the present invention which utilizes the magnetic field component of the electromagnetic radiation carried over the power transmission lines rather than the electric field component which the prior art has concentrated on.
The present invention comprises a method and system for communicating information between subscribers over power transmission lines which normally convey electrical power to a plurality of diverse electrical sites for providing electrical power to electrical devices disposed at these diverse electrical sites. The subscribers on the communication network are located at these electrical sites. The electrical power conveyed over the power transmission lines is in the form of electromagnetic radiation which has an electrical field component and an orthogonal and interdependent or associated magnetic field component. The information, such as telephonic voice communication or other data, is transmitted in the magnetic field component of the electromagnetic radiation carried over the power transmission line, such as by exciting the field with a MASER, in order to enable communication between the subscribers at the various electrical sites. The system enables selective reception of the transmitted communication using standard information protocol addressing. The signal transmitted from the MASER, which employs a microwave generator, is a coherent acoustic type signal which has an output frequency which is sufficient to cause atomic transition from E1 to E2 within the magnetic field of continua around the power transmission line at the specific magnetic moment that exists as a result of the electricity flowing through the power transmission line, such as in the range of 30 GHz to 300 GHz. The MASER provides an inverted atomic population by pumping directly, through a Q-switch and a synthetic aperture lens, into the atomic population of the electromagnetic wave carried over the power transmission line to produce acoustic wave oscillation at the appropriate atomic transition frequency. The MASER output is transmitted within the existing magnetic flux envelope created by the magnetic field of the electromagnetic radiation carried over the power transmission line and the power transmission line acts as a magnetic waveguide for the coherent magnetic frame emissions from the MASER. Inductive coupling is used to receive the transmitted information and detects and converts the electromagnetic field into electrical signals for analysis, verification, and distribution to the designated subscriber or subscribers in accordance with the information protocol. The signal processing of the information is accomplished through a neural network such as a reduced coulomb energy network or RCE and conventional fuzzy tools. The system may selectively route and process messages and control event management for the various electromechanical devices connected to the power line. The transmitted signal is transparent to the power transformers, can be transmitted over great distances, at high speed, without suffering any significant signal attenuation, is relatively unaffected by noise, and has no affect on external long wave radio communications. In this regard, MASER amplifiers, such as employed in the present invention, can provide noise figures in the microwave and radio frequency ranges that are lower than those for any other electronic type of amplifiers at the same frequencies.